I'm not saying it's all bad, but that movie has not aged as well as my teenage self in 2000 was confident it would.
Fight Club is a movie starring Brad Pitt and Edward Norton that was released in 1999, based on the novel of the same name by Chuck Palahniuk. It included this oft-quoted and parodied line: "The first rule of Fight Club is you do not talk about Fight Club." Randall twists this iconic line by asking that if you ever meet him in real life, "Do not talk about the movie Fight Club."
The movie has been fiercely debated by critics, primarily regarding whether it makes a sophisticated philosophical statement about society and consumerism or whether it is just a movie with lots of fighting and mischief. It has a large and devoted fanbase who are convinced that the film is brilliant and transformative, and who have a reputation for wanting to discuss it at every opportunity.
In the title text, Randall explains his position further. He evidently saw it as a teenager and was implied to be a big fan initially, but now doesn't feel that it's aged well. As an adult, he doesn't claim the film is all bad, but has lost his enthusiasm for it, and appears to have no interest to discuss it with people who are still fans.
"This conversation is over" is also a line from the movie, used to bluntly cut off any further discussion. Cueball ironically uses a quote from the movie to make it clear he has no interest in discussing the movie.